Aerodynamics Explained | With CFI Bootcamp | Power Hour Lessons

[@mikeshiflett97]

You are correct. Most of the FAA handbooks are still dated but they are the sources we have to teach from until they change. I hope that will be soon. It’s true that there is not equal transit time. The air does accelerate but not so each molecule meets the separated one. Thanks for the comment

[@MegaDeano1963]

At 23:50 the best evidence I,ve seen to stall being caused by loss of lift rather than increase in drag . Good proof also of why bournoulli theorem is very applicable to planes

[@MSDASmusic]

The paid version of Wind Tunnel is no longer available in the US.

[@hunterfagan6272]

I’m a little bit confused about the part at 31:31. I thought lift is acts perpendicular to the relative wind?

[@XPLAlN]

....in case you are still interested, you are correct that lift acts perpendicular to the RAF by definition. I think what he did in the video was use the phrase 'total lift' in place of what is more properly called 'total reaction' Total reaction is sometimes labelled as the 'resultant' of lift and drag vectors, although imo it is more correct to think of lift and drag as vector components of the total reaction.

[@terrellroberts5876]

great video, but I found an error. The lowest point on the power required curve is not Vg, it is actually the minimum sink speed. The best glide is the airspeed at which a straight line from the origin is tangent to the power required curve.

[@GZA036]

After having them make and fly a paper plane to dispel equal transit time or the need for camber to make lift, I the use a flat plate wing model as this is the simplest kind of wing and a flat plate will not generate any lift a 0 AOA which avoids all of those silly Bernoulli myths.(A symmetrical aerofoil will also behave in the same way but then they try to invent ways to use the camber). "Lift is a force resulting from turning a fluid. Any pressure differential in the fluid flow is primarily a result of mechanical intervention between the static air and the moving wing. While all 3 of Newton's laws apply to varying degrees, lift primarily rests with #2 and the concept that f=ma. If we visualise the problem from the 'real world' perspective (moving wing-static air) using smoke-lines, it is easy to see that as soon as the plate is inclined to the relative airflow, it generates a bow wave under the lower leading edge and the change of state/velocity/pressure under the wing is caused by the wing pushing the air downwards and forwards which contributes a great deal of the lift. This is the 'fluid pushing back' as you stated. At the same time the air divides and follows the upper surface and changes its velocity(no need for Coanda theories-it has no choice). As it 'turns the corner' it is now in the 'leeward' side of the plate and so the pressure is slightly lower as a result of the wing's motion and displacement of the air by the inclined lower surface. Simultaneously, as it changes direction and the wing continues forward the pressure/density drops as the air 'spreads out' causing a further slight drop in /pressure/density and at higher speeds or loads a temperature drop. (Hence the need for supercritical wings to minimise standing shock waves and the visible ectoplasm as military fast jets pull high 'G' in a humid atmosphere) Here's where it gets sticky for some: The acceleration people go on about, (the air 'speeds up' over the upper surface - hence lower pressure.) is clearly a 'downward' acceleration not a chord-wise one. In fact in wind tunnel terms (moving air - static wing) the upper surface air SLOWS DOWN (viscosity, form drag, induced drag)compared to the free stream air. This is most noticeable at the boundary layer and decreases with distance from the wings fluid field. I typically use the Cambridge University video pulsed smoke to demonstrate this kzbin.info/www/bejne/bIbPpHSoq8eHm9F9n because it clearly shows that in both cases the wing moves/pulls/pushes the boundary and local static air along in its direction of motion. It can also be seen that the relative airflow actually begins to divide before it comes into contact with the leading edge because of this bow wave or pressure 'bubble'. That this bow wave is a considerable influence can be see in air to air refuelling. A C-5 hooking up to a KC-135 will push the tail of the tanker upwards while remaining well behind and attached to the boom. Modern supercritical wings(used on all airliners) have a pronounced and progressive inverse camber (belly) in their lower wing surfaces to increase the 'downwards/forwards' bow wave lift effect and a reflex curve at the trailing edge to turn the lower surface airflow downwards and more closely align it with the flow shedding from the upper surface (which on SC wings tends to be much flatter). So lift is caused by turning, pushing and pulling the static air (flow field) around the wing. The pressure differential is a by-product of this not the cause.

[@XPLAlN]

>>”While all 3 of Newton's laws apply to varying degrees, lift primarily rests with #2 and the concept that f=ma.” They do not apply to varying degrees. They are physical laws, so by definition they all apply completely at all times, everywhere. The only caveat being that the 1st law is just a special case of the 2nd law. >>”as it changes direction and the wing continues forward the pressure/density drops as the air 'spreads out' causing a further slight drop in /pressure/density and at higher speeds or loads a temperature drop. (Hence the need for supercritical wings to minimise standing shock waves and the visible ectoplasm as military fast jets pull high 'G' in a humid atmosphere)” What a load of sciolistic waffle. Air density changes are negligible at low Mach number: think take-off when high coefficient of lift is required at low speed. Yet airplanes still manage. A hydrofoil generates huge amounts of lift with zero density change. In subsonic aerodynamics as taught to pilots you only consider density changes of the freestream and take it as constant from there.. >>”Here's where it gets sticky for some: The acceleration people go on about, (the air 'speeds up' over the upper surface - hence lower pressure.) is clearly a 'downward' acceleration not a chord-wise one. In fact in wind tunnel terms (moving air - static wing) the upper surface air SLOWS DOWN (viscosity, form drag, induced drag)compared to the free stream air. This is most noticeable at the boundary layer and decreases with distance from the wings fluid field.” You seriously need to go and learn fluid dynamics from the beginning, by which I mean you need elementary physics first to relieve you of the severe misconceptions you hold. Firstly this: >>”the acceleration people go on about is clearly a 'downward' acceleration not a chord-wise one” No it isn't. When people talk about the variation of velocity in the context of Bernoulli they are referring to velocity along the streamline. They are not denying that streamlines can curve up or down. >>”In fact in wind tunnel terms (moving air - static wing) the upper surface air SLOWS DOWN (viscosity, form drag, induced drag)compared to the free stream air.” No it doesn't. The upper streamlines above the boundary layer reach a PEAK velocity higher than freestream before slowing down again as they approach the trailing edge. Nobody is claiming they come off the trailing edge faster than freestream (that would be propulsion!) This is the very reason that the normal shock wave begins on the upper surface of the wing at significantly less than Mach 1 flight speed - because the peak local velocity at that point on the wing has reached M1 already. >>”air SLOWS DOWN (viscosity, form drag, induced drag)compared to the free stream air This is most noticeable at the boundary layer and decreases with distance from the wings fluid field.” That is nonsense. By definition, all streamlines outside “the wings fluid field” are at freestream conditions. As for the boundary layer, it is the thin layer where friction slows the streamlines to the assumed 'no slip condition' at the surface. The Bernoulli equation is a simplification that ignores effects found in the boundary layer. Anyone who has studied fluid dynamics knows this. >>”I typically use the Cambridge University video pulsed smoke to demonstrate this kzbin.info/www/bejne/bIbPpHSoq8eHm9F9n because it clearly shows that in both cases the wing moves/pulls/pushes the boundary and local static air along in its direction of motion” You cannot possibly deduce such a thing from that video because the smokelines do not extend out to freestream conditions. There is no debate about whether the flow field has overall gained some momentum in the direction of flight. The fact of drag confirms it to be so. But equally, there is no debate about whether there is a region above the airfoil where the air has attained a velocity higher than flight speed (before it then slows down again). Once again, this fact can be confirmed by simply knowing that a normal shock wave begins on the top surface before the airplane reaches M1. >>”It can also be seen that the relative airflow actually begins to divide before it comes into contact with the leading edge because of this bow wave or pressure 'bubble'” Obviously the flow splits to go round the airfoil. Who knew? But Relative Airflow does not divide. The airflow divides. Relative airflow is just a reference. Yes you can say there is a “pressure bubble” because the hypothetical dividing streamline is trading kinetic energy for static pressure until it reaches a theoretical point on the airfoil known as the stagnation point - Bernoulli again - which could be thought of as the 'epicentre' of a 'pressure bubble'. >>”Modern supercritical wings(used on all airliners) have a pronounced and progressive inverse camber (belly) in their lower wing surfaces to increase the 'downwards/forwards' bow wave lift effect and a reflex curve at the trailing edge to turn the lower surface airflow downwards and more closely align it with the flow shedding from the upper surface (which on SC wings tends to be much flatter).” The whole concept of the supercritical wing is to reduce the normal shock (hence reduce and delay wave drag) caused by the accelerated flow over the top surface. The very existence of this wing profile on transonic airplanes that cannot achieve M1 flight speed should alert you to the fact that velocity over the top surface reaches a peak velocity that is higher than flight speed. But for some unfathomable reason the penny has not dropped. Instead you think it is evidence of the opposite. >>”So lift is caused by turning, pushing and pulling the static air (flow field) around the wing.” To finish off with such an oxymoron kind of sums up your incoherent attempt to educate the internet on a subject you are clearly ill equipped to lecture on.